Force multiplying type archery bow

ABSTRACT

An archery bow formed by a main member adapted to be grasped by an archer with a limb pivotally attached to each opposite end thereof, with construction for reducing the pull or draw poundage of the bow between undrawn and fully drawn positions of a bow string. The limbs are pivoted relative to the main member and lesser force is required to maintain the reduced poundage than that required at the fully drawn position absent the reducing means. The bow has an element for limiting the amount of rotation of the limbs relative to the main member that is gripped by a user. Each limb has an anti-friction member that bears against a resilient member and is biased by the resilient member when pivoted relative to the main member.

United States Patent 1191 Smith 1 51 May28, 1974 FORCE MULTIPLYING TYPE ARCHERY BOW George C. Smith, 1738 Edeline Ave., McKinleyville, Calif. 95521 Filed: Nov. 29, 1972 Appl No.: 310,448

[76] Inventor:

[56] References Cited UNITED STATES PATENTS 12/1969 Allen 124/24 R 7/1971 Storer .L 124/23 R Primary Examiner-Richard C. Pinkham Assirtant Examiner william R. Browne [57] ABSTRACT An archery bow formed by a main member adapted to be grasped by an archer with a limb pivotally attached to each opposite end thereof, with construction for reducing the pull or draw poundage of the bow between undrawn and fully drawn positions of a bow string. The limbs are pivoted relative to the main member and lesser force is required to maintain the reduced poundage than that required at the fully drawn position absent the reducing means. The bow has an element for limiting the amount of rotation of the limbs relative to the main member that is gripped by a user. Each limb has an anti-friction member that bears against a resilient member and is biased by the resil- 12 Claims, 8 Drawing Figures FORCE MULTIPLYING TYPE ARCHERY BOW This invention is directed to improvements in archery bows and more specifically to bows having means which increase the release energy thereof while at the same time reducing the holding force of comparable bows in the drawn position whereby arrow speed, trajectory, and accuracy due to ease of aiming at a lower holding force are all increased.

In the June 1972 issue of Sports Field, at page 38, reference was made to a compound bow which because of its pulley arrangement makes possible shorter bow limbs and increases energy which drives arrow. Faster arrow means flatter trajectory and greater accuracy. This increases clean kill probability."

This represents an advance over the typical long bows of years past wherein the force required to draw the bow string increased as the bow was bent until reaching a maximum force at full draw. With such conventional bows maximum pull poundage is exerted at full draw and aim accuracy is lessened because the high holding force at full draw reduces the steadiness of aim as might otherwise be achieved under conditions of less than maximum pull. Such disadvantages are somewhat negated in compound bows as the energy graph is ellipsoidal in configuration, rather than triangular as in conventional bows, so that for how limbs of a given stiffness and greater limb tip travel an increase in energy is developed for a standard draw. Thus an archer of lesser physical prowess should expect more favorable results with less input energy in the use of a compound bow than a conventional bow.

Compound bows are particularly instrumental in raising the number of bow hunters in this country to approximately one million, a four-fold increase in the past ten years. Unfortunately the so-called pulley arrangement of most compound bows is rather complex and creates difficulties in arming, sighting, firing and track ing, particularly in heavy foilage.

In keeping with the present invention a compound bow is provided which is as operative with as without a pulley arrangement, includes means for reducing the pull poundage of the bow between undrawn and fully drawn positions, and includes means in the form of deflectable resilient elements for imparting a force to pivo'tally mounted limbs which carry the bow string whereby accuracy of aim is not only increased but trajectory and arrow speed is likewise favorably increased over known archery bows, compound or other.

A further object of this invention is to provide a novel archery bow wherein the pivotally mounted limbs each carry a roller in contact with the deflectable resilient elements for increasing the speed of movement of the limbs from the drawn to the undrawn positions of the bow thus increasing arrow speed and, of course, arrow trajectory.

Still another object of this invention is to provide a novel archery bow wherein means are provided for compensating for the movement of the pivotally mounted limbs to equalize the movement of each between the drawn and undrawn positions, thereby increasing accuracy, with adjusting means also being provided for variations in condition of use as well as an archer's physical prowess.

A final object of this invention is to provide a novel archery bow of the type heretofore set forth including the provision of a pulley arrangement for making possible shorter limbs while increasing arrow speed thereby gaining greater accuracy through flatter arrow trajectory.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claimed subject matter, and the several views illustrated in the accompanying drawings.

IN THE DRAWINGS FIG. 1 is a side elevational view of a novel archery bow constructed in accordance with this invention, and

illustrates a main member pivotally carrying at each end a limb which in turn carries a roller bearing against a deflectible resilient element for adding energy to an arrow after release while a lesser force is required to maintain the drawn position during aiming.

FIG. 2a is a side elevational view of the bow of FIG. 1, and illustrates by the unnumbered headed arrows the pivotal movement of various components from the undrawn position of the bow to its fully drawn position.

FIG. 2b is an illustration of the how similar to FIG.

2a, and illustrates the full drawn position of the bow with unnumbered headed arrows indicating the movement of components from thefull drawn toward the undrawn position of FIG, 2a.

FIG. 3 is an end elevational view of the bow of FIG. 1 looking from right-to-left with portions broken away for clarity, and illustrates details of the pivotal mounting of the limbs to a main member of the bow,

FIG. 4 is a side elevational view of the bow with a portion thereof broken away and shown in section for clarity, and illustrates the manner in which oneof two identically pivoted limbs is moved by the bow string to its fully drawn position.

FIG. 5 is an enlarged fragmentary sectional view taken generally along the line 5-5 of FIG. 1, and illustrates further details of the pivotal mounting of one of the limbs to the main member as well as one of the deflectable resilient elements for bearing against a roller carried by the limb to augment the speed of arrow flight upon the release of the bow string.

FIG. 6 is a side elevational view of another bow constructed in accordance with this invention similar to the bow of FIG. 1, but illustrates leaf spring type elements for imparting force to the limbs for increased arrow speed as well as a pulley arrangement which permits the use of shorter limbs than the arrangement of FIG. 1 devoid of the pulley arrangement.

FIG. 7 is a side elevational view of the bow of FIG. 6, and illustrates in phantom and solid outline, respectively, the undrawn and fully drawn positions of the bow.

A novel bow constructed in accordance with this invention is generally designated by the reference numeral 10 (FIGS. 1 and 3) and includes a main member or handle section ill provided with a conventional arrow rest 12 and carrying at remote opposite ends 13, 14 a pair of plates l5, l6 and 17, 18, respectively. The plates 15-18 could be constructed as an integral onepiece unit of the main member 11 or can be simply separate plates secured by conventional fastening means to opposite sides of the main member 11. In any event the plates 15, 16 and 17, 18 form two generally U- shaped gaps 20, 21, respectively, therebetween which accommodate portions of respective arms or limbs 22, 23.

The limbs 22, 23 have first ends 24, 25, respectively, notched to receive a bow string 26 having conventional serving 27. At approximately the midpoint of each limb 22, 23 the same is pivotally mounted by a conventional pivot pin 27, 28, respectively, between the plates 15, 16 and 17, 18, respectively. Thus the upper arm 22, as viewed in FIG. 1, will pivot about the pivot pin 27 in a clockwise direction as the bow string 26 is drawn from its undrawn to its fully drawn position (FIGS. 20 and 2b, respectively) whereas like movement results in counter-clockwise pivoting of the lower limb 23.

The limbs 22, 23 carry respective metal or similar rollers 30, 31 at respective ends 32, 33 of the limbs 22, 23. The rollers 30, 31 bear against force imparting means in the form of a pair of deformable, resilient, reboundable metallic elements 34, 35 carrying respective stops 36, 37. The elements 34, 35 are secured to a front face (unnumbered) of the handle section 11 by U-bolts 40, 41 and wing nuts 42, 43, respectively. The bight portion (unnumbered) of the U-bolts 40, 41 embrace the respective elements 34, 35 whereas the legs (unnumbered) of the U-bolts 40, 41 pass through the main 1 member 11 and are fastened opposite the elements 34,

35 by the wing nuts 42, 43.

The how further includes means 45, 46 to maintain the limbs 22, 23 in the same angular position relative to the handle section 1 1 irrespective of the position of the bow string 27 anywhere between the undrawn position of FIG. 2a and the fully drawn position of FIG. 2b. The means 45, 46 include a pair of wires 47, 48, respectively, each having a turnbuckle 50, 51 which is, in turn, secured to an eye 52, 53 of the respective limbs 22, 23. Opposite ends (unnumbered) of the wires 47, 48 are secured by eyes (unnumbered) to the ends of the arms 23, 22, adjacent the rollers 30, 31.

In conventional archery bows in which the main sectionand limbs are not pivotally mounted relative to each other, each limb bends and poundage progressively increases to a maximum at full draw. However, with respect to the present bow 10 as the bow string 26 is drawn from the undrawn position (FIG. 2a) to the full drawn position (FIG. 2b) the pull or poundage progressively builds to a maximum, which is not at full draw and thereafter reduces to as low as value as zero holding pounds in the full drawn position (FIGS. 2b and 4). Though the holding poundage is zero during the transition between maximum poundage and full draw the elements 34, 35 are deflected, in the manner best illustrated in FIGS. 2b and 4. Thus, as the bow string is drawn between the positions illustrated in FIGS. 2a and 2b the poundage or force when at a maximum is in effect transferred into the elements 34, 35 and upon release of the bow string 26 the inherent reboundable nature of the eiements 34, 35 return themselves from the position of FIGS. 2b and 4 to the positions of FIGS. 1 and 2a thus launching the arrow at a speed determined by the maximum poundage earlier built up in these elements 34, 35.

The means 45, 46 are necessary to maintain the limbs 22, 23 identically disposed in angular relationship to the main frame 11 at any time between -full drawn (FIG. 2b),and no draw (FIG. 2a). The means 45, 46 are necessary because after passing maximum poundage further pivotal movement of the limbs 22, 23 toward the full draw position (FIG. 2b) results in a decrease in holding poundage, to as low as zero pounds, and in order to maintain the limbs 22, 23 identically aligned to the main section or member 11 for accurate aiming and trajectory, the means 45, 46 are providedflhus at any position of draw up to full draw of FIG. 2b the limbs 22, 23 are at the same angle relative to the main member or section 11.

The elements 36, 37 carried by the respective elements 34, 35 prevent the rollers 30, 31, respectively, from moving beyond the unfastened freeends of the elements 34, 35. The elements 36, 37 are furthermore adjustable in slots 54 (FIG. 4) running lengthwise in each of the elements 34, 35. By appropriately moving the elements 36, 37 in the slots 54 and fastening the same at any of a number of positions the deflection of the elements 34, 35 can be controlled with maximum deflection occurring upon the contact of the rollers 30, 31 with the respective elements 36, 37. In this manner maximum load poundage transferred to the elements 34, 35 can be adjustably varied as found necessary or desirable depending, of course, upon such things as the physical capability of the archer, conditions of foilage, hunting or sport shooting, etc.

Reference is made to FIGS. 6 and 7 which illustrate another bow 10' having elements similar to the bow 10 and those bearing like though primed reference numerals. Essentially the bow It) differs from the bow 10 in that the limbs 22', 23 are shorter and to achieve maximum draw length and arrow velocity a pulley system, generally designated by the reference numeral 60 is provided. The pulley system 60 includes four pulleys 61-64, the first two of which are conventionally rotatably mounted between a pair of plates (unnumbered) which are in turn fixed to the ends of the limbs 22', 23'. The pulleys 63, 64 are pivotally secured in a conventional manner to the main section or member 11 with each limb 22, 23 also carrying respective eyelet 67, 68. The cable arrangement 60 is coupled to the bow string 26' by endless elements 72, 73. The element 72 is coupled by a conventional fastener to one end of the bow string 26 and therefrom is partially entrained about the pulley 61, the pulley 63, and its end is fastened to the eyelet 67. Likewise the element 73 is coupled to the opposite end of the bow string 26' by a conventional fastener 71 and is entrained about the pulley 62, the pulley 64 and fastened to the eyelet 68 of the limb 23'.

As the bow 10 is drawn from its undrawn position (phantom outline in FIG. 7) to its fully drawn position (solid line in FIG. 7) each pulley 61, 62 passes out approximately one inch of the cord 72, 73, respectively, because of the progressive decrease in the distance between the tips of the limbs 22', 23' as they approach each other toward the full drawn position. Thus, the draw length is increased since in efiect the draw string 26' may be considered to be lengthened by the amount of the cable 72, 73 drawn out beyond the rollers 61, 72 toward the full drawn position of the bow which in effect further increases velocity and thus improves arrow trajectory. The elements 34', 35 operate in the manner heretofore discussed relative to the bow 10, but the elements 34, 35' are illustrated as leaf springs which are similarly deflectable by the rollers 30' and 31' and similarly reboundable to the position illustrated in FIG. 6 under their own power due to the inherent resiliency thereof.

While preferred forms and arrangements of parts have been shown in illustrating the invention, it is to be clearly understood that various changes in detail and arrangement of parts may be made without departing from the spirit and scope of this invention.

1 claim:

1. An archery bow comprising a member adapted to be grasped by an archer and having opposite ends, a limb pivotally attached to said member at a point intermediate its length, said limb having at least one free end, a bow string attached to said limb, whereby upon drawing said bow string the limb will pivot relative to said member, means for reducing the pull poundage of said bow between undrawn and fully drawn positions of said bow string whereat each said limb is pivoted and lesser force is required to maintain the reduced poundage than that required at the fully drawn position of the bow absent said reducing means, means for imparting a biasing force against an end of said limb most adjacent said member for urging said bow limb in a direction toward the undrawn position of said bow string, and said force imparting means is an elongated cantilever spring element secured to said member which pushingly bears against said limb end normally biasing the same toward its undrawn position.

2. The archery bow as defined in claim 1 including an elongated element extending between said limb and said member, and means on said element variably limiting the angular displacement of the terminal free end of limb relative to said member in the undrawn position of said string.

3. The archery bow as defined in claim 1 including a pulley carried by each of said limbs remote from said member, and said bow string being at least partially entrained about said pulleys and attached to said limbs.

4. The archery bow as defined in claim 1 wherein an anti-friction member carried by said limb end bears against said member.

5. The archery bow as defined in claim 3 including a pulley carried by said limb remote from said member, and said bow string being at least partially entrained about said pulley and attached to said limb.

6. The archery bow as defined in claim 1 including a pulley carried by said limb remote from said member, and said bow string being at least partially entrained about said pulley and attached to said limb.

7. An archery bow comprising a member adapted to be grasped by an archer and having opposite ends, a limb pivotally attached to each of said member ends, each limb having first and second ends respectively removed from and adjacent to the associated member end, a bow string spanning the distance between said limb first ends whereby upon drawing said bow string said limbs will pivot relative to said member, means for reducing the pull poundage of said bow between undrawn and fully drawn positions of said bow string whereat said limbs are pivoted relative to said member and a lesser force is required to maintain the reduced poundage than that required at the fully drawn position of the bow absent said reducing means, each limb being pivoted between its ends to said member, and means for imparting a biasing force against a free terminal free end of each limb during pivoting of said limbs for urging said limbs in a direction toward an undrawn position of said how string, said force imparting means comprising an elongated cantilever spring element secured to said member which pushingly bears against said limb end normally biasing the same toward its undrawn position.

8. The archery bow as defined in claim 7 wherein each force imparting means is a deflectable resilient element carried by said member against which bears an end of each associated limb.

9. The archery bow as defined in claim 6 including roller means for reducing friction disposed between each limb and said member, and each roller means being in engagement with one of said deflectable resilient elements.

10. The archery bow as defined in claim 3 wherein each roller means is carried by the second end of each limb.

11. The archery bow as defined in claim 7 including means for preventing overpivoting of each limb beyond a predetermined desired fully drawn position of said bow string.

12. The archery bow as defined in claim 7 including a pulley carried by each limb first end, a pair of pulleys carried by said member, and said bow string is entrained at least partially about each pulley with ends thereof fastened to said limbs. 

1. An archery bow comprising a member adapted to be grasped by an archer and having opposite ends, a limb pivotally attached to said member at a point intermediate its length, said limb having at least one free end, a bow string attached to said limb, whereby upon drawing said bow string the limb will pivot relative to said member, means for reducing the pull poundage of said bow between undrawn and fully drawn positions of said bow string whereat each said limb is pivoted and lesser force is required to maintain the reduced poundage than that required at the fully drawn position of the bow absent said reducing means, means for imparting a biasing force against an end of said limb most adjacent said member for urging said bow limb in a direction toward the undrawn position of said bow sTring, and said force imparting means is an elongated cantilever spring element secured to said member which pushingly bears against said limb end normally biasing the same toward its undrawn position.
 2. The archery bow as defined in claim 1 including an elongated element extending between said limb and said member, and means on said element variably limiting the angular displacement of the terminal free end of limb relative to said member in the undrawn position of said string.
 3. The archery bow as defined in claim 1 including a pulley carried by each of said limbs remote from said member, and said bow string being at least partially entrained about said pulleys and attached to said limbs.
 4. The archery bow as defined in claim 1 wherein an anti-friction member carried by said limb end bears against said member.
 5. The archery bow as defined in claim 3 including a pulley carried by said limb remote from said member, and said bow string being at least partially entrained about said pulley and attached to said limb.
 6. The archery bow as defined in claim 1 including a pulley carried by said limb remote from said member, and said bow string being at least partially entrained about said pulley and attached to said limb.
 7. An archery bow comprising a member adapted to be grasped by an archer and having opposite ends, a limb pivotally attached to each of said member ends, each limb having first and second ends respectively removed from and adjacent to the associated member end, a bow string spanning the distance between said limb first ends whereby upon drawing said bow string said limbs will pivot relative to said member, means for reducing the pull poundage of said bow between undrawn and fully drawn positions of said bow string whereat said limbs are pivoted relative to said member and a lesser force is required to maintain the reduced poundage than that required at the fully drawn position of the bow absent said reducing means, each limb being pivoted between its ends to said member, and means for imparting a biasing force against a free terminal free end of each limb during pivoting of said limbs for urging said limbs in a direction toward an undrawn position of said bow string, said force imparting means comprising an elongated cantilever spring element secured to said member which pushingly bears against said limb end normally biasing the same toward its undrawn position.
 8. The archery bow as defined in claim 7 wherein each force imparting means is a deflectable resilient element carried by said member against which bears an end of each associated limb.
 9. The archery bow as defined in claim 6 including roller means for reducing friction disposed between each limb and said member, and each roller means being in engagement with one of said deflectable resilient elements.
 10. The archery bow as defined in claim 3 wherein each roller means is carried by the second end of each limb.
 11. The archery bow as defined in claim 7 including means for preventing overpivoting of each limb beyond a predetermined desired fully drawn position of said bow string.
 12. The archery bow as defined in claim 7 including a pulley carried by each limb first end, a pair of pulleys carried by said member, and said bow string is entrained at least partially about each pulley with ends thereof fastened to said limbs. 